M. A. Hegazy

Synthesis and inhibitive performance of novel cationic and gemini surfactants on carbon steel corrosion in 0.5 M H2SO4 solution

Novel cationic and gemini surfactants were synthesized and characterized. The corrosion inhibition efficiency of the synthesized surfactants was studied, on carbon steel in 0.5 M H2SO4, by weight loss, potentiodynamic polarization and EIS. The results revealed that both cationic and gemini surfactants effectively inhibited the corrosion of carbon steel in 0.5 M H2SO4. The corrosion inhibition efficiencies obtained were calculated by weight loss and electrochemical experiments. The potentiodynamic polarization studies revealed that the inhibitors acted as mixed-type inhibitors. Thermodynamic parameters of adsorption and kinetic were obtained from weight loss at different temperatures (20–60 °C). The inhibitor adsorption on the carbon steel surface obeyed the Langmuir isotherm.

The biocidal effect of a novel synthesized gemini surfactant on environmental sulfidogenic bacteria: planktonic cells and biofilms.

A cationic gemini surfactant was synthesized and characterized. The surfactant was successfully applied as a biocide against environmental sulfidogenic bacteria in the bulk phase (planktonic) and on the surface (biofilm). The activity of the synthesized surfactant was discussed based on the redox potential and the sulfide productivity in the bulk phase. The cultivated biofilm structure analysis and corrosion rate were estimated on the metal surface. The lowest metal corrosion rate was recognized at a concentration of 1mM with a metal corrosion inhibition efficiency of 95%. The synthesized gemini surfactant prevented the biofilm formation at a concentration of 0.1mM. The synthesized gemini surfactant displayed a broad spectrum antibacterial activity against Gram-positive and Gram-negative bacteria.

Studying the corrosion inhibition of carbon steel in hydrochloric acid solution by 1-dodecyl-methyl-1H-benzo[d][1,2,3]triazole-1-ium bromide

A novel cationic surfactant 1-dodecyl-methyl-1H-benzo[d][1,2,3]triazole-1-ium bromide (1-DMBT) was synthesized and its structure was confirmed by using 1H NMR and FTIR spectroscopic analysis. The surface tension and electrical conductivity of that surfactant were measured and its critical micelle concentration and some of its surface properties also were determined and discussed. The inhibition performance of the prepared (1-DMBT) on the corrosion of carbon steel in 1.0 M HCl solution was investigated at different concentrations and temperatures by using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The obtained results revealed that the synthesized (1-DMBT) regards as a good corrosion inhibitor for carbon steel in HCl medium and acts mainly as a mixed-type inhibitor. The inhibition of (1-DMBT) efficiency increases with increasing its concentration but decreases with rise in temperature. Such inhibition is related to the adsorption of the surfactant on the metal surface and the adsorption process obeys the Langmuir isotherm.

Sulfidogenic-corrosion inhibitory effect of cationic monomeric and gemini surfactants: planktonic and sessile diversity

A cationic monomeric surfactant (CMS) and a cationic gemini surfactant (CGS) were successfully synthesized and characterized. A comparison of the CMS and CGS metal corrosion inhibitory effects was carried out on the basis of protecting a metal surface from cultivated salinity (3.18% NaCl) and an environmental sulfidogenic bacterial activity in a reactors bulk phase (planktonic) and on a metal surface (sessile). Environmental sulfidogenic bacterial consortia were originated from an oil-field water tank. The sulfidogenic bacterial activities were evaluated based on redox potential and sulfide concentrations in the reactors bulk phase. In addition, changes in biofilm structures and constituents and the metal corrosion rate were determined to estimate changes on metal surfaces. Results in the reactors bulk phases showed that at high surfactant (CMS, CGS) concentrations, a considerable decline in the redox potential was observed and the sulfide productivity was completely suppressed. The synthesized surfactants showed the highest metal corrosion inhibition efficiencies of 92% and 94% at concentrations of 10 mM and 1 mM for the CMS and the CGS, respectively. In addition, the synthesized CMS and CGS showed nonspecific antibacterial activity against Gram-positive and Gram-negative bacterial-standard strains.